Consecutive monoculture regimes differently affected the diversity of the rhizosphere soil viral community and accumulated soil-borne plant viruses

Viruses interact with nearly all organisms on Earth, thereby influencing biogeochemical cycles, agriculture, and health. However, less is known about the composition and function of viruses in agricultural rhizosphere soils, especially under consecutive monoculture regimes. Our qRT-PCR analysis in this study showed that consecutive monoculture regimes significantly increased the content of pathogenic Broad bean wilt virus 2, Turnip mosaic virus, and Cucumber mosaic virus in Radix pseudostellariae roots at different growth stages. Metatranscriptome analysis indicated that consecutive monoculture altered the rhizosphere soil viral community structure, composition, and habitat niche breadth and accumulated pathogenic plant viruses in the rhizosphere soil. In addition, 54 unique carbohydrate metabolism-related open reading frames (ORFs) were detected as encoding carbohydrate-active enzymes (CAZymes) in viromes, including glycoside hydrolases and glycosyl-transferase activities. Our results also showed that the soil viral richness and the Shannon index displayed a negative correlation with bacterial abundance and a positive correlation with fungal abundance. Soil pH, total nitrogen, available phosphorus, and phenolic acids were the key abiotic drivers of the soil viral community composition. Our study provides new insights into how consecutive monoculture regimes shape the soil viral community composition and further influence plant viral diseases.